Currently available microprocessors designed for space and military applications do not meet the performance and functional requirement integrated circuits of many proposed new systems. For example, the current offerings from manufacturers of military and space components are limited to technologies circa 150 nm and above. These offerings are limited by the intrinsic capabilities of the semiconductor facilities being used, with investment to get those fabs to state-of-the-art manufacturing being in the hundreds of millions of dollars and the operating costs and sustaining engineering costs making the investment unaffordable even for the government.
However, commercially available microprocessors meet the performance and function requirements of such space and military applications, but are not radiation hardened sufficiently for these applications. For example, commercial integrated circuits have higher performance, function, and density compared with integrated circuits designed for space and military applications; however, designs for such commercial integrated circuits result in failure caused by Single Event Upsets (SEUs) in space applications. For example, ionizing radiation in space (and ground) based applications directly upsets storage circuits, such as DRAMs, SRAMs, register files and flip-flops. Moreover, radiation events in combinational logic create voltage glitches that can be latched. Also, SEUs may cause the circuit to perform incorrect or illegal operations; whereas, an accumulation of radiation over a long period of time may additionally lead to complete device failure.
In space applications, the major radiation sources are high-energy protons and high-energy heavy ions (from helium up to about any heavy stable isotope). The high-energy cosmic protons and ions are known to produce secondary fragments which cause SEUs and single event latchups (SELs), as well as total failure resulting from total dose (long accumulation of radiation) in semiconductor ICs. Fluxes of cosmic protons and heavy ions can be estimated by models like Cosmic Ray Effects on Microelectronics (CREME) software packages.
For applications on the ground, a major source of radiation is from neutrons. These terrestrial neutrons interact with the devices and the packaging materials to produce secondary (spallation) ions that cause upsets (mainly single event upsets SEUs). The spectra of the secondary ions depend on the device back end of the line (BEOL) materials. The terrestrial neutron flux has been measured and modeled very accurately. In modern nuclear physics and high-energy physics experiments, man-made radiation environments are often generated near the microelectronics that control the detector systems, because the primary beam produces secondary particles (e.g., protons, heavy ions, pions and other particles) which can cause SEUs and SELs.
These upsets, e.g., SEUs, SELs multibit upsets (MBUs), single-bit failures and total failure, have been observed for currently available commercial device configurations (e.g., 65 nm, 45 nm, etc.). Minimizing the occurrence of such upsets with minimal change to design and process would allow the use of close derivatives of commercial components with close to commercial performance, function, and density with a minimal schedule delay. Thus, a new solution is required which meets the needs for performance and function and which also provides adequate radiation tolerance, at minimal cost and changes in current processes and designs.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.